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Collaborative Research: Reframing Notions of Wet vs. Dry Subduction: The Search for a Deep Fluid Signature in Subducted Continental Crust Using Coupled O, B, and Fe Isotopes

合作研究：重新定义湿俯冲与干俯冲的概念：使用 O、B 和 Fe 耦合同位素寻找俯冲大陆壳中的深层流体特征

基本信息

批准号：
1822524
负责人：
Catherine Macris
金额：
$ 24.84万
依托单位：
Indiana University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1822524&HistoricalAwards=false
关键词：
Collaborative Research Reframing Notions Wet

项目摘要

Subduction zones represent not only the main mechanism of mass transfer between the Earth's surface and interior, but also the setting for a majority of large earthquakes and a source of significant volcanic activity, both of which have dramatic and direct effects on human civilization. The presence, scale, and nature of fluids in deep portions of subduction zones are undoubtedly important factors in the generation of both earthquakes and magma, and therefore must be identified and characterized. This study will contribute to our current understanding of deep fluids in subduction zones, and potentially establish a new method for studying them. It would also, as the title suggests, reframe notions of wet versus dry subduction, which may open the door to other ideas and methods for studying subduction zone processes. This project will provide training and research opportunities for a diverse group of graduate and undergraduate students. Outreach activities at local GK-12 schools will expose potential future scientists to cutting edge Earth Science.Small volumes of continental crust surrounded by oceanic crust may be subducted to ultrahigh-pressure (UHP) depths and exhumed in the early stages of orogeny. These small, subducted blocks of continental crust can preserve evidence of large-scale, deep subduction fluid metasomatism. This team hypothesizes that the Tso Morari terrane, a young UHP locality in the NW Himalaya, represents a small, early-subducted continental mass that likely experienced metasomatism at UHP in the subduction zone. Recent advances have led to novel isotopic and geochemical proxies to fingerprint the origin of subduction-derived fluids and melts both in exhumed subduction materials and arc magmas. In particular, boron is expected to be enriched in devolatilized fluids and depleted in the corresponding host rocks with boron isotopic values providing a sensitive indication of the extent of devolatilization. Additionally, iron isotope systematics are emerging as a potentially powerful tracer of the nature of slab derived fluids. This project will combine these novel proxies with the more established and traditional tracers of subduction fluids, including oxygen isotopes, thermodynamic and fluid modeling, bulk-rock geochemistry, ferrous/ferric iron ratios on a suite of UHP rocks and associated ophiolite/melange from the Tso Morari.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

俯冲带不仅是地球表面和内部之间物质转移的主要机制，而且是大多数大地震的发生地和重大火山活动的来源，这两者都对人类文明产生巨大和直接的影响。俯冲带深部流体的存在、规模和性质无疑是地震和岩浆生成的重要因素，因此必须加以识别和表征。这一研究将有助于我们目前对俯冲带深部流体的认识，并可能建立一种新的研究方法。正如标题所示，它还将重新构建湿与干俯冲的概念，这可能为研究俯冲带过程的其他想法和方法打开大门。该项目将为不同的研究生和本科生群体提供培训和研究机会。在当地GK-12学校的外展活动将使未来的潜在科学家接触到尖端的地球科学。被海洋地壳包围的小块大陆地壳可能会俯冲到超高压（UHP）深度，并在造山运动的早期阶段被挖掘出来。这些小的俯冲陆壳块可以保存大规模的深俯冲流体交代作用的证据。该研究小组假设，Tso Morari Eye是喜马拉雅西北部一个年轻的超高压地点，代表了一个小型的早期俯冲大陆块体，可能在俯冲带的超高压中经历了交代作用。最近的进展导致了新的同位素和地球化学代理指纹的起源俯冲派生流体和熔体在折返俯冲物质和弧岩浆。特别是，硼预计将富集在脱挥发分的流体和相应的寄主岩石与硼同位素值提供了一个灵敏的指示脱挥发分的程度贫化。此外，铁同位素系统学正在成为一个潜在的强大的示踪剂的性质板衍生流体。该项目将联合收割机将这些新的代用指标与更成熟和传统的俯冲流体示踪剂结合起来，包括氧同位素、热力学和流体模拟、大块岩石地球化学、一套超高压岩石和伴生蛇绿岩的亚铁/三价铁比值，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的评估来支持。影响审查标准。